The invention relates to a process for producing a multi-chamber packaging tube, more particularly a tube of plastic material.
Multi-chamber packaging tubes are tubes with at least one partition or separating wall accommodated therein, to define a plurality of chambers for receiving respective packaging materials which are to be kept separate until they are delivered, for example components of a consumer material or item, which are to be brought together only when the item is to be used. Consumer items or materials of that kind are increasingly in the forefront in the field of technology, hygiene, cosmetics and pharmaceuticals.
There are various processes for the production of multi-chamber tubes, which in principle are distinguished as two kinds, more specifically assembler processes and forming processes. The main difference between these kinds of processes is that, in the assembler process, tubes with separating walls are assembled from individual parts while, in the forming process, a tube body portion with separating wall or a head with a separating wall, that is to say always at least two tube components, are formed in one working operation and then for example the tube body portion and the separating wall with head are brought together or the head and the separating wall with the tube body portion are brought together.
In one form of assembler process a prefabricated tube body portion is connected to a tube head which is also prefabricated. A separating wall which is of a fold-shaped configuration and which is resilient in its longitudinal and transverse directions is inserted into the tube body portion. The separating wall, more specifically at one of its transverse sides, is selectively connected to the tube head by adhesive, while the other transverse side is joined to the closure seam of the tube. Due to the transversely and/or longitudinally acting spring forces which are inherent in the separating wall, the separating wall is braced with its longitudinal sides against the interior of the tube body portion and, insofar as there is no adhesive join to the interior of the tube head, between the closure seam and the tube head.
In that process the separating wall is fitted into the interior of a prefabricated tube, and that is an operating procedure which can only be automated with difficulty. In addition special means have to be provided, for connecting the separating wall to the closure seam in a spring-biased condition, after filling of the chambers (U.S. Pat. No. 3,877,520 to Dukess).
In a further assembler process a separating wall is introduced into a prefabricated tube and is braced against the inside surface of the tube body portion along the longitudinal sides of the separating wall, by means of flaps. To form the flaps, the separating wall is spaced with respect to the longitudinal edges thereof, which act as hinges for the flaps. The bracing effect is effected by making use of the return force or memory of the plastic material or materials, to move the flaps in a direction towards the inside surface of the tube body portion. That process suffers from the disadvantage that the separating wall has to be introduced into the tube with the flaps in a condition of being bent over, and that results in complication of the loading apparatus which, by virtue of the mode of operation involved therewith, set limits on the output of the process in the sense of the number of assembled tubes per unit of time (U.S. Pat. No. 5,628,429 to Enamelon Inc.).
One kind of forming process is wherein firstly a head with a separating wall is formed and then the head produced in that way is joined to a tube body portion. A disadvantage of that process is generally the expense involved in automation thereof (British patent specification No 1 030 275 to Rosier).
Another forming process provides that a tube body portion with separating wall is formed by a winding operation around a mandrel or bar with longitudinal seam welds after the winding operation is concluded. A disadvantage of that process is that the winding operation does not make it possible to form any separating wall portions which could be brought into engagement with a shoulder and/or an outlet or nozzle of a tube head. That is obviated by virtue of the fact that prefabricated tube heads have the pitch relationships with which, when joining the tube head, separating walls are to be brought to bear against or otherwise connected to the xe2x80x9cwinding tubexe2x80x9d (U.S. Pat. No 3,948,704 to The Proctor and Gamble Comp.).
The above-outlined assembler processes are generally implemented by starting from prefabricated tubes (head and tube body portion combined) while the basic starting point adopted in the forming process is a prefabricated tube body portion with head. The basic operation in both processes, namely producing a tube by forming a tube head on a tube body portion by press shaping or injection molding or by mounting a tube head to a tube body portion, using a finished head, have been developed to a high technical level which ensures a high level of output of tubes per unit of time. That output is markedly reduced by the process steps involved in the assembler and forming processes, and this factor lies in substantial separation of the latter procedure from the basic operation, that is to say the production of a tube from a tube body portion and a head.
An object of the present invention is to provide a process for producing multi-chamber tubes, which avoids the disadvantages of the assembler and forming processes as outlined above.
Another object of the invention is to provide a process for producing multi-chamber packaging tubes, which affords a simple reliable operating procedure with enhanced functional versatility and improved automation options.
Still a further object of the invention is to provide a process for the production of multi-chamber tubes, which combines process steps in a procedure attaining comparable production times to a process for producing single-chamber tubes.
In accordance with the principles of the invention the foregoing and other objects are attained by a process for the production of a multi-chamber packaging tube of plastic material, the tube comprising a tube body portion, a tube head and at least one separating wall which is accommodated in the tube body portion and the tube head. The tube head is mounted to the tube body portion by means of a tool including a die and a bar as tool halves. The bar is loaded with a separating wall and subsequently a tube body portion or vice-versa.
As will be seen from the description hereinafter of a preferred embodiment of the invention a process step which is common to the above-indicated prior tube-production processesxe2x80x94namely loading a bar or mandrel with a tube body portionxe2x80x94is supplemented by or preceded by an operation of loading a bar or mandrel with a prefabricated separating wall. The operation of loading the bar with a separating wall can be effected substantially more quickly than the operation, which is included in the assembler process, of introducing a separating wall into a tube or the operation, in the forming process, of joining a preshaped tube body portion to a head which is designed for example to extend a separating wall of the tube body portion into the head, whereby the process according to the invention, in regard to its output of multi-chamber tubes per unit of time, comes very close to the output of single-chamber tubes, so that the process according to the invention can provide for the production of a multi-chamber tube, with comparable economy to single-chamber tubes.
The procedure in accordance with the invention can be carried into effect as long as a female mold or die, referred to herein generally as the die, and a bar or mandrel, referred to herein generally as the bar, are determining technical means for carrying the process into effect. In the operation for forming the head on the tube, the die and the bar act as a mold for forming a head, insofar as liquid plastic material is injected under pressure into the mold (injection molding) or a given amount of plasticised plastic material, under the development of pressure, is shaped to form a head, by means of the bar (press shaping). As the bar in both cases carries the tube body portion and in accordance with the invention the separating wall, the tube body portion, in the procedure for forming the head, is joined to the latter, just as is the separating wall which projects into the head, unless precautions were taken not to join the separating wall to the head as it is being formed. In the operation for disposing the head on the tube, the die does not have a molding action in regard to the head, but acts as a means for receiving and holding a prefabricated head which substantially corresponds to its contour, and as a device for fusing the edge of the head and/or of an end of the tube body portion which is positioned on a bar, for connecting the two together. In this case also the die may locally limitedly cause melting of the head and/or the tube body portion with separating wall in such a way that the tube body portion and if desired the separating wall are connected to the head. Thus, in regard to the process according to the invention, the die is not limited in terms of its function to a shaping component of the process, but it also extends to a holding and heating function. The same applies for the bar which, in the forming process, acts as a holding and shaping element while in the mounting process it acts as a holding means solely for the tube body portion and the separating wall. In accordance with the invention, and with that background in mind, the die and the bar are functionally technical equivalents for the forming and mounting processes.
Irrespective of whether multi-chamber tubes are provided with finished heads or whether they have heads which are formed thereon, they can be of various configurations in regard to the arrangement of separating walls within the tube. In that respect, it is assumed that the transverse side of a separating wall corresponds to the internal contour of a head and is in engagement with that contour. Thus the separating wall may adjoin the inside surface, in which case the transverse side can also be so contoured that an extension acting as a wall engages through the outlet or nozzle opening of the head. With that separating wall configuration, the following arrangements of a separating wall in a tube are possible as alternative fixing modes and can be carried into effect with the process according to the invention:
a) a separating wall is connected neither to the head nor to the tube body portion. The separating wall is resiliently locked against the tube body portion;
b) connection of the transverse side of a separating wall to the head; the longitudinal sides of the separating wall remain unconnected to the inside surface of the tube body portion, but bear thereagainst in a prestressed or non-prestressed condition;
c) the transverse side of the separating wall remains bearing against the head but unconnected, the longitudinal sides are connected to the inside surface of the tube body portion; and
d) the transverse side is connected to the tube head and the longitudinal sides are connected to the inside surface of the tube body portion.
The connection of the transverse side of a separating wall to the head can be made in various ways. When using injection molding the transverse side is molded or cast into place, while when press shaping is used the transverse side, that is to say a respective edge strip portion of the transverse side, is formed into the plasticised plastic material (PE) during the operation of forming the head. When a tube is provided with a prefabricated tube head, then the transverse side can be secured to the inside surface by the adoption of an adhesive join or a mechanical fixing, for example in the form of a groove which runs along the inside surface of the head and into which an edge portion of the transverse side can be inserted. If the separating wall is to remain unconnected to the head, means are to be provided, in the injection operation and the operation of forming the head on the tube body portion, which cover over the edge portions of the transverse side, with respect to the injected or plasticised plastic materials. Suitable means for that purpose could be plates or discs which cover over the front face of a bar with inserted separating wall, edge portions and cut edges. If the longitudinal sides of the separating walls remain unconnected to the inside surface, then they bear against the inside surface, applying pressure thereagainst. The pressure can be produced by virtue of the configuration of the separating wall, for example of a S-shaped cross-section and thus resiliently in the direction of opening of the S-shaped configuration or by virtue of return or restoration forces caused by a memory effect, for example produced by rounded flanges along the longitudinal sides of the separating walls which, like tubes, comprise plastic materials. The longitudinal sides can be connected to the inside surface of a tube body portion by adhesive means or welding, the latter with the application of heat and pressure. In that case the plastic material of the separating wall, that is to say for example of a flange which extends along the longitudinal side and possibly a strip which is disposed opposite the flange, along the inside surface of the tube body portion, is plasticised or melted and the flange and strip are pressed together.
Further objects, features and advantages of the invention will be apparent from the following description of a preferred embodiment of the invention.